Abstract: Environmental vibration induced by underground moving metro trains has aroused much attention of the society as more and more subway tunnels are constructed in saturated soft soils in the coastal area of China. Taking the Shanghai metro line 2 for example, response of saturated soft soil layers induced by subway train in the shield tunnel is analyzed by using cyclic mobility constitutive model and water-soil coupled method, including ground surface vibration acceleration and dynamic displacement, as well as the dynamic response of excess pore water pressure(EPWP). The acceleration level of ground surface is adopted to evaluate the intensity of ground surface vibration. Numerical results show that dynamic response of saturated soil is much smaller than that of dry soil, vibration on the ground surface also presents distinct differences in the horizontal direction and vertical direction. As for excess pore water pressure, it diminishes along vertical tunnel axial direction, whereas it increases first and then decreases in the vertical profile several meters away from tunnel center. The results can provide guidance for vibration mitigation design and settlement control measures for nearby structures.

Key words: vibration load of train, cyclic mobility model, vibration acceleration, acceleration level, vibration displacement, excess pore water pressure(EPWP)